Articles & Case Studies


Posted: Monday 9th August 2010

As part of Essex & Suffolk’s ongoing inspection and maintenance program, Stonbury were contracted to carry out refurbishment works to one of their surge vessels. This included fitting a new manway and recoating the internal surfaces.

To begin the works a full ultrasonic thickness test was done around the area where the new manway was going to be installed. This was to determine the actual steel thicknesses. From these readings we produced design calculations to prove that the new manway met the code requirements. These where approved which allowed fabrication of the manway to start and then be installed on site.

A full internal access scaffold was erected to facilitate the internal refurbishment works. After this was installed we fully removed the existing coating system (bitumen) by grit blasting, with particular attention being paid to extract all dust and debris from the surge vessel outside into a skip without any of the debris escaping from the vessel and entering the valve house. After grit blasting was complete, a full visual inspection was carried out of the internal condition of the steel work, including ultrasonic thickness tests where they felt any loss of section has occurred. A full magnetic particle inspection test was then carried out on all the welds associated with the new manway which was passed.

The scaffolding was then removed with all external connections to the vessel isolated and blanked off. The vessel was filled with water, gradually vented of air and brought up to the required pressure for its test. This was witnessed and passed by the third party insurers. The vessel was then drained and scaffolding was re-erected and allowed to fully dry. The internal surfaces of the vessel where then coated with a solvent free urethane to a minimum dry film thickness (D.F.T) of 1000 microns (1mm) to give a maintenance free life of 20 years. Scaffolding was then dismantled and all external connections where re-fitted.

After seven days of the product curing, the vessel was sterilised and the manway was closed. Any external areas of the vessel (around the newman way) where coated with a solvent free epoxy to a minimum D.F.T of 500 microns. This in turn was coated with a polyurethane top coat to match the existing colour and then the vessel was then returned to service.

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